Conventionally, there is a technique of determining an electrical discharge state between poles of an electrode of an electrical discharge machine and a workpiece, thereby controlling the electrical discharge machine by using the determination result.
Patent Literature 1 describes that an electrical discharge is generated between poles in an electrical discharge machine to detect the gradient of a discharge voltage change, the discharge level, and high-frequency components, and an electrical discharge state is determined by combining two or more kinds of detection signals thereof. According to Patent Literature 1, accurate detection and observation can be performed and optimum control of respective units can be performed.
Patent Literature 2 describes that an electrical discharge is generated between poles in an electrical discharge machine, a high-pass filter extracts only high-frequency components of a voltage waveform between the poles, a rectifier rectifies the high-frequency components, an integrating device integrates rectified outputs, a comparing device compares an integrated voltage with a reference voltage, and a machining condition control device checks an output of the comparing device and extends a quiescent period when discriminating that the electrical discharge state is poor. According to Patent Literature 2, detection of an electrical discharge machining state can be performed accurately, and generation of a continuum arc between the poles can be prevented, thereby enabling to prevent damages on an electrode or a workpiece.